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Muscular dystrophy includes a diverse group of inherited muscle diseases characterized by wasting and weakness of skeletal muscle. Mutations in dysferlin are linked to two clinically distinct muscle diseases, limb-girdle muscular dystrophy type 2B and Miyoshi myopathy, but the mechanism that leads to muscle degeneration is unknown. Dysferlin is a homologue(More)
Vesicle-vesicle fusion initiated in cell cytoplasm by high Ca(2+) can rapidly erect large membrane boundaries. These might be used as a 'patch' for resealing plasma membrane disruptions. Three central predictions of this 'patch' hypothesis are here established in sea urchin eggs. First, we show that surface markers for plasma membrane protein and lipid are(More)
Plasma membrane disruptions are resealed by an active molecular mechanism thought to be composed, in part, of kinesin, CaM kinase, snap-25, and synaptobrevin. We have used HRP to mark the cytoplasmic site of a mechanically induced plasma membrane disruption. Transmission electron microscopy revealed that vesicles of a variety of sizes rapidly (s) accumulate(More)
Biological membranes are often described as 'self-sealing' structures. If indeed membranes do have an inherent capacity for repair, does this explain how a cell can rapidly reseal a very large (1-1000 microm(2)) disruption in its plasma membrane? It is becoming increasingly clear that, in nucleated animal cells, the cytoplasm plays an active and essential(More)
Many metazoan cells inhabit mechanically stressful environments and, consequently, their plasma membranes are frequently disrupted. Survival requires that the cell rapidly repair or reseal the disruption. Rapid resealing is an active and complex structural modification that employs endomembrane as its primary building block, and cytoskeletal and membrane(More)
A microneedle puncture of the fibroblast or sea urchin egg surface rapidly evokes a localized exocytotic reaction that may be required for the rapid resealing that follows this breach in plasma membrane integrity (Steinhardt, R.A,. G. Bi, and J.M. Alderton. 1994. Science (Wash. DC). 263:390-393). How this exocytotic reaction facilitates the resealing(More)
We describe a simple method for loading exogenous macromolecules into the cytoplasm of mammalian cells adherent to tissue culture dishes. Culture medium was replaced with a thin layer of fluorescently labeled macromolecules, the cells were harvested from the substrate by scraping with a rubber policeman, transferred immediately to ice cold media, washed,(More)
Severe vitamin E deficiency results in lethal myopathy in animal models. Membrane repair is an important myocyte response to plasma membrane disruption injury as when repair fails, myocytes die and muscular dystrophy ensues. Here we show that supplementation of cultured cells with α-tocopherol, the most common form of vitamin E, promotes plasma membrane(More)
On demand, rapid Ca(2+)-triggered homotypic and exocytic membrane-fusion events are required to repair a torn plasma membrane, and we propose that this emergency-based fusion differs fundamentally from other rapid, triggered fusion reactions. Emergency fusion might use a specialized protein and organelle emergency response team that can simultaneously(More)
We have combined fluorescent analogue cytochemistry with fluorescence photobleaching recovery to measure the mobility of fluorescently labeled actin and other labeled test proteins microinjected into living amoebae. Bovine serum albumin, ovalbumin, and ribonuclease A have a cytoplasmic mobility, expressed as a diffusion coefficient, that is 1/2 to 1/3 of(More)